It's a fairly recent happening, as I KNOW it worked a month ago.
I was riding home from school last night when a guy at a stoplight told me it was out.
Sure enough, it was.
Fuses are good, and I know the bulb is good as I "reversed" the bulb and hit the brakes - the small filament came on then.
But the bulb back in correctly, hit the brakes, and the "bright" filament was lit.
I haven't made any changes to anything, so I'm kind of stumped.